8/05/2009 @ 1:58PM

Could Bacteria Be A Throat-Cancer Culprit?

That’s the question raised by a new study by researchers at New York University Langone Medical Center. They found that people who have either chronic heartburn or a more serious, precancerous condition called Barrett’s esophagus had completely different kinds of microbes living in their throats than those who were healthy. The research was published in the current issue of the medical journal Gastroenterology.

“This is the type of thing that one hopes more people will do,” says Jonathan Eisen, a professor at the UC-Davis Genome Center who was not involved in the work. He cautions that it is “way too early” to say that the bacteria are causing disease. “All they have right now is a correlation.”

The NYU researchers sequenced bacteria DNA samples from the throats of 12 healthy people, 12 with gastro-esophageal reflux disease (GERD) and 10 with Barrett’s. In the healthy people, 82% of throat bacteria were Streptococcus.

In those with esophageal disease, the bacteria in the throat were more like those in the stomach; only a quarter of them were Strep. Scientists divide bacteria into so-called “gram positive” varieties like Strep, which lack rigid cell walls and can be stained with dye, and “gram negative” ones that have cell walls and aren’t dyeable. The throats of the people with GERD and Barrett’s were full of gram negatives.

This opens up several possibilities, says Zhiheng Pei, the paper’s lead author. The bacteria could actually be a cause of GERD, and acid reflux actually follows the bacterial change. Another possibility is that they get flushed up by the acid reflux. But Barrett’s, which results from chronic GERD, can lead to adenocarcinoma of the throat, a cancer. Perhaps, Pei says, exposure to the wrong kind of bacteria, not just acid, is one cause of the disease.

If the bacteria really play a causal role in disease, the upset will be as big as the discovery 20 years ago that bacteria, not just stomach acid, are the major cause of ulcers. GERD and Barrett’s are currently treated with stomach acid drugs like
AstraZeneca’s
Nexium and
Wyeth’s
Protonix.

A great deal more work needs to be done to sort out what’s happening here. Pei says this initial study cost $1 million, because traditional gene sequencing is so expensive. But now newer technologies are dramatically reducing the cost of such work.
Roche’s
454 Life Sciences Unit,
Illumina
and Life Technologies all make gene sequencers that are dramatically decreasing the cost of DNA sequencing while increasing the speed.

The U.S. government is spending $115 million to fund a Human Microbiome Project that aims to understand how the microbes in the human body affect overall health (see: “Our Germs, Ourselves”).

There are 100 million bacteria teeming inside the human body, 10 times as many as there are human cells. This is possible because bacteria are one one-thousandth the size of a human cell. This bacterial horde has both positive and negative implications for health–it is implicated in obesity, asthma and irritable bowel syndrome. Scientists hope they might someday treat and prevent disease by shifting the bacterial balance.